Planing refers to the hydrodynamic process whereas, on increasing speed, the boat is lifted up relative to the water surface by dynamic pressure acting over the surface of the boat hull bottom. This dynamic pressure is an increasing function of boat speed. At rest, the boat is supported (floats) by pressure provided by hydrostatics at zero speed, resulting in the boat being positioned deeper in the water, displacing a larger water volume than in planning.
Conflicting conditions of operation therefore exist with the typical planning craft:
1. displacement (low speed) mode, requiring relatively large displaced volume and larger wetted surface area, and PA1 2. planing (high speed) mode, requiring relatively small displacement and smaller wetted surface area.
The conflict is that, in order to have the area needed for displacement operation, excessive area and its accompanying excessive drag tend to occur in high speed planing operation.
Modern planing craft resolve this conflict to some degree by the use of stepped sterns, lifting strakes, internal chines, and/or combinations thereof. [Note FIG. 1 ("Prior Art").] All three of the hull form modifications shown function to separate the flow in steady planing (as well as in seaway slamming) to produce a smaller area for reduced planing resistance (and impact acceleration).
In the current state-of-the-art of internal chines and lifting strakes, relatively small "flow trips" are used that are often not effective. The main shortcoming is that the flow separated at the chine, or strake, can reattach, and thus the prior art has not consistently achieved the relatively low wetted surface area needed for optimum planing performance. [Note FIG. 2 ("Prior Art").]
The present invention over-comes the prior art deficiencies.